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In recent years, a large body of literature has accumulated around the topic of research paper recommender systems. However, since most studies have focused on the variable of accuracy, they have overlooked the serendipity of recommendations, which is an important determinant of user satisfaction. Serendipity is concerned with the relevance and unexpectedness of recommendations, and so serendipitous items are considered those which positively surprise users. The purpose of this article was to examine two key research questions: firstly, whether a user’s Tweets can assist in generating more serendipitous recommendations; and secondly, whether the diversification of a list of recommended items further improves serendipity. To investigate these issues, an online experiment was conducted in the domain of computer science with 22 subjects. As an evaluation metric, we use the serendipity score (SRDP), in which the unexpectedness of recommendations is inferred by using a primitive recommendation strategy. The results indicate that a user’s Tweets do not improve serendipity, but they can reflect recent research interests and are typically heterogeneous. Contrastingly, diversification was found to lead to a greater number of serendipitous research paper recommendations.

Abstract: Effects of mechanical compression and PTFE content on the through-plane gas permeability of gas diffusion layers (GDLs) of PEM fuel cells are investigated both experimentally and theoretically. A new test bed is designed and built which allows pressure drop and air flow rate measurement for various GDL samples. The measured values are used to calculate the through-plane permeability. Various GDLs are obtained and tested over a wide range of PTFE content and compression ratio. The experimental data show a reverse relationship between the through-plane permeability and both PTFE content and mechanical compression. An existing model for through-plane permeability of planar fibrous structures is revisited to develop a model that accommodates effects of PTFE content and mechanical compression. The proposed model captures the trends of the experimental data for the through-plane permeability, measured in the present study or reported by others. [Copyright &y& Elsevier]

A new technique was introduced for sand stabilization and re-vegetation by use of lignin sand stabilizing material (LSSM). LSSM is a reconstructed organic compound with lignin as the most dominant component from the extracts of black-liquor issued by straw pulp paper mills. Unlike the polyvinyl acetate or foamed asphalt commonly used for dune stabilization, the new material is plant-friendly and can be used with virescence actions simultaneously. The field experimental study was conducted since 2001 in China's Northwest Ningxia Hui Autonomous Region and has been proved that LSSM is effective in stabilizing the fugitive dunes, making the arenaceous plants survive and the bare dune vegetative. The advisable solution concentration is 2% and the optimal field spraying quantity is 2.5 L/m^2. The soil nutrients of the stabilized and greened dune, such as organic matter, available phosphorous and total nitrogen are all increased compared with the control treatment, which is certainly helpful to the growth of arenaceous plants. The technique is worthwhile to be popularized because it is provided not only a new method for desertification control but also an outlet for cleaning contaminants issued from the straw paper mills. [ABSTRACT FROM AUTHOR]

In order to design an optimal reinforcement of steel thin-walled beams with composite materials, it is worth analyzing two important, although often overlooked issues, which are the selection of the appropriate thickness of the adhesive layer and the effective anchoring length of the composite tape. This paper, which is part of a wider laboratory study devoted to the strengthening of thin-walled steel profiles, focuses on the second issue. The paper involves a description of laboratory four-point bending tests during which ten thin-walled steel beams made of a rectangular section with dimensions of 120 × 60 × 3 and a length of 3 m were tested. Two beams were taken as reference beams, and the other eight were reinforced using Sika CarboDur S512 carbon fiber composite tape, assuming four different effective anchorage lengths. The impact of the length of the anchoring of the composite tape on the value of the displacements and strains of the tested beams and on the value of the destructive load that caused tape detachment was analyzed. The following phase was numerical analyses carried out in the Abaqus program, which showed high consistency with the results of laboratory tests. In reference to the conducted tests, it was observed that the increase in the anchoring length of the composite tape has a slight impact on the change in the value of strains and displacements in the tested beams. Nevertheless, the increase in the effective anchorage length has a significant impact on the load value at which the composite tapes are detached from the surface of the steel thin-walled beam. [ABSTRACT FROM AUTHOR]

The special large-slope V-shaped structure of underwater tunnels changes the ventilation characteristics during tunnel construction, making the traditional experience limited. Therefore, it is urgent to study the influence of the special structure on the safety of the air environment during construction. In this paper, a series of small-scale experiments were conducted to investigate the ventilation characteristics of V-shaped tunnels. The coupled effects of ventilation parameters (distance of duct outlet from working face  L 0 , air velocity at the duct outlet  u 0 ) and structural characteristics (digging length  L d , slope of the uphill section  θ) were considered. The extreme slope of the V-shaped tunnel of 8% was considered. The flow field and pollutant transport law were determined by using CO as a tracer in the experiments. The results show that  u 0  has a positive impact on the air return velocity, while  L d  has a negative impact, and neither of the other two factors has a significant effect. The transport characteristics of CO in V-shaped tunnels differ from those in flat tunnels, with the former tending to cause unconventional areas of high pollutant concentrations in the horizontal sections. Furthermore, the correlations between CO concentration and distance, ventilation time, and the influence factors discussed in this paper are derived from the experimental results. The conclusions provide guidance for the construction of V-shaped tunnels to prevent air pollution in the construction environment and to improve the working conditions of laborers. Additionally, it can also enrich the ventilation experience in tunnel construction. [ABSTRACT FROM AUTHOR]

In recent years, computer vision-based structural displacement acquisition technique has received wide attention and research due to the advantages of easy deployment, low-cost, and non-contact. However, the displacement field acquisition of large-scale structures is a challenging topic as a result of the contradiction of camera field-of-view and resolution. This paper presents a large-scale structural displacement field calculation framework with integrated computer vision and physical constraints using only one camera. First, the full-field image of the large-scale structure is obtained by processing the multi-view image using image stitching technique; second, the full-field image is meshed and the node displacements are calculated using an improved template matching method; and finally, the non-node displacements are described using shape functions considering physical constraints. The developed framework was validated using a scaled bridge model and evaluated by the proposed evaluation index for displacement field calculation accuracy. This paper can provide an effective way to obtain displacement fields of large-scale structures efficiently and cost-effectively. [ABSTRACT FROM AUTHOR]

A new configuration of continuum surgical robot is proposed, whose skeleton is composed of inner and outer layers. The outer layer is composed of miniature rotating modules connected in series and connected by orthogonal hinges, which can ensure the ability to resist unconventional torsion without losing the degree of freedom. The inner layer is a central support column with superelasticity. When bending, its superelasticity can make the overall configuration biased toward constant curvature bending, which is convenient for motion control and according to the new configuration, this paper establishes the kinematics model of the robot. Finally, the motion control experiment of the continuum robot is carried out. After the experiment, the average positioning error of the robot is 2.674 mm, and the average repetitive positioning error is 2.625 mm. Both are less than 2 % of the robot length, verifying the accuracy of the model. [ABSTRACT FROM AUTHOR]

This paper proposes a version of the deep-sea environment simulated test system for subsea control modules to solve the problem of incomplete testing systems for electro-hydraulic subsea control modules. Based on the subsea control module test requirements specified in APISTD17F, the test system in this paper is a highly integrated system, including a test hydraulic power unit, a control module test bench, a signal simulator, an electronic test unit, an umbilical simulator, a high-pressure chamber, and an incubator. Firstly, the design indicators of the test system were determined by analyzing the various functions of the subsea control module and its working environment. Secondly, the design scheme for the test system was proposed, and a detailed design was carried out. Finally, a hydro-electrical subsea control module for the Bohai Sea was fully tested with this system, with tests including the qualification test and the factory acceptance test. The test results show that all parts of the test system coordinated well and have achieved the design indicators, and the test system can simulate the working environment and complete a land test. The effectiveness and feasibility of the test system have been verified through the test. By adopting this system, the risk of subsea control module failure can be minimized, laying the foundations for future research and improvement of subsea control module testing equipment. [ABSTRACT FROM AUTHOR]

Calculating the parameters of the ground shock induced by an underground explosion is a complex energy coupling problem. It is difficult to establish a unified ground shock coupling law from limited test data. This paper summarizes the research results obtained at home and abroad and systematically analyzes the coupling mechanism of craters formed by an underground explosion and the ground shock. The differences between the concepts of "closed-explosion critical depth" and "equivalent closed-explosion critical depth" are clearly explained. The spreading of the ground shock energy is attributed to the explosive expansion of the air cavity, revealing a linear relationship between the volume of the cavity region (or the volume of the crack region) and the ground shock energy associated with the underground explosion. The proportionality factor is related to the mechanical properties of the medium and is independent of the magnitude of the explosion equivalent. Based on this, a theoretical calculation formula and conversion method for the ground shock coupling coefficient were established. Explosion tests were conducted in clay and Plexiglass under varying burial depths. The test results were consistent with the theoretically calculated results. Our study provides a theoretical basis for the design of explosion-resistant structures in underground engineering. [ABSTRACT FROM AUTHOR]

The food crisis has increased demand for agricultural resources due to various factors such as extreme weather, energy crises, and conflicts. A solar greenhouse enables counter-seasonal winter cultivation due to its thermal insulation, thus alleviating the food crisis. The root temperature is of critical importance, although the mechanism of soil thermal environment change remains uncertain. This paper presents a comprehensive study of the soil thermal environment of a solar greenhouse in Jinzhong City, Shanxi Province, employing a variety of analytical techniques, including theoretical, experimental, and numerical simulation, and deep learning modelling. The results of this study demonstrate the following: During the overwintering period, the thermal environment of the solar greenhouse floor was divided into a low-temperature zone, a constant-temperature zone, and a high-temperature zone; the distance between the low-temperature boundary and the southern foot was 2.6 m. The lowest temperature in the low-temperature zone was 11.06 °C and the highest was 19.05 °C. The floor in the low-temperature zone had to be heated; the lowest value of the constant-temperature zone was 18.29 °C, without heating. The minimum distance between the area of high temperature and the southern foot of the solar greenhouse was 8 m and the lowest temperature reading was 19.29 °C. The indoor soil temperature tended to stabilise at a depth of 45 cm, and the lowest temperature reading at a horizontal distance of 1400 mm from the south foot was 19.5 °C. The Fluent and LSTM models fitted well and the models can be used to help control soil temperature during overwintering in extreme climates. The research can provide theoretical and data support for the crop areas and the heating of pipelines in the solar greenhouse. [ABSTRACT FROM AUTHOR]

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